As climate change accelerates, extreme weather events become more severe and frequent. We analyzed the datasets of decade-long observation (2005–2020) of mercury (Hg) stored in two subtropical
evergreen forests to understand the impacts of extreme weather on the sequestration of atmospheric Hg in forest ecosystems. Results show a weak correlation between litterfall Hg and atmospheric Hg0 concentration.
Droughts and snowstorms significantly disturb Hg accumulation in litterfall and soils. Litterfall Hg concentration and deposition both display an increasing trend during the period of extended droughts in 2011–2014, but a decreasing trend after droughts. This is caused by the water stress that influences the change of tree physiology and processes of foliage Hg0 uptake. Snowstorm damages large areas of canopy,which leads to substantial canopy epiphyte cover mixed into the forest floor, thus considerably increasing soil Hg concentrations. Over a decadal timescale, soil Hg variabilities are shaped by the combined effects of atmospheric Hg inputs and processes of organic soil mineralization mediated climatic factors. Our study highlights that the accelerated climate change increases the unpredictability of Hg accumulation in terrestrial ecosystems. Future studies are needed for better understanding the response of Hg biogeochemical cycling to climate change among different terrestrial biomes.